Auto merge of #129670 - est31:cfg_attr_crate_type_name_error, r=Urgau

Make deprecated_cfg_attr_crate_type_name a hard error

Turns the forward compatibility lint added by #83744 into a hard error, so now, while the `#![crate_name]` and `#![crate_type]` attributes are still allowed in raw form, they are now forbidden to be nested inside a `#![cfg_attr()]` attribute.

The following will now be an error:

```Rust
#![cfg_attr(foo, crate_name = "foobar")]
#![cfg_attr(foo, crate_type = "bin")]
```

This code will continue working and is not deprecated:

```Rust
#![crate_name = "foobar"]
#![crate_type = "lib"]
```

The reasoning for this is explained in #83744: it allows us to not have to cfg-expand in order to determine the crate's type and name.

As of filing the PR, exactly two years have passed since #99784 has been merged, which has turned the lint's default warning level into an error, so there has been ample time to move off the now-forbidden syntax.

cc #91632 - tracking issue for the lint

2 files changed, 19 insertions, 14 deletions

diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index af56169fd60..21dbc251b06 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -23,8 +23,9 @@ use thin_vec::ThinVec;
 use tracing::instrument;
 
 use crate::errors::{
-    FeatureNotAllowed, FeatureRemoved, FeatureRemovedReason, InvalidCfg, MalformedFeatureAttribute,
-    MalformedFeatureAttributeHelp, RemoveExprNotSupported,
+    CrateNameInCfgAttr, CrateTypeInCfgAttr, FeatureNotAllowed, FeatureRemoved,
+    FeatureRemovedReason, InvalidCfg, MalformedFeatureAttribute, MalformedFeatureAttributeHelp,
+    RemoveExprNotSupported,
 };
 
 /// A folder that strips out items that do not belong in the current configuration.
@@ -360,20 +361,10 @@ impl<'a> StripUnconfigured<'a> {
             item_span,
         );
         if attr.has_name(sym::crate_type) {
-            self.sess.psess.buffer_lint(
-                rustc_lint_defs::builtin::DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-                attr.span,
-                ast::CRATE_NODE_ID,
-                BuiltinLintDiag::CrateTypeInCfgAttr,
-            );
+            self.sess.dcx().emit_err(CrateTypeInCfgAttr { span: attr.span });
         }
         if attr.has_name(sym::crate_name) {
-            self.sess.psess.buffer_lint(
-                rustc_lint_defs::builtin::DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-                attr.span,
-                ast::CRATE_NODE_ID,
-                BuiltinLintDiag::CrateNameInCfgAttr,
-            );
+            self.sess.dcx().emit_err(CrateNameInCfgAttr { span: attr.span });
         }
         attr
     }
diff --git a/compiler/rustc_expand/src/errors.rs b/compiler/rustc_expand/src/errors.rs
index 0fdccb08918..5682c574552 100644
--- a/compiler/rustc_expand/src/errors.rs
+++ b/compiler/rustc_expand/src/errors.rs
@@ -468,6 +468,20 @@ pub(crate) struct GlobDelegationOutsideImpls {
 }
 
 #[derive(Diagnostic)]
+#[diag(expand_crate_name_in_cfg_attr)]
+pub(crate) struct CrateNameInCfgAttr {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(expand_crate_type_in_cfg_attr)]
+pub(crate) struct CrateTypeInCfgAttr {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(expand_glob_delegation_traitless_qpath)]
 pub(crate) struct GlobDelegationTraitlessQpath {
     #[primary_span]